Dell wont power up

[Draggar]

Get yourself a Dell power supply tester - it saves a lot of work and stress. (Dell part# FT295 - it tests the power supply connections, HDD connectors, 3.5": floppy connector, and SATA power cables).

Now - when you push the power button - by "nothing happening" you mean none of the fans spin, no BIOS beep, no lights, etc..

You checked the power button. Check the reset switch (if the PC has one) - it could be stuck. (no need to short - just disconnect)

Other than clearing the BIOS - disconnect ALL peripherals (all drives etc..). Remove the video card (if it has a separate one), clean off the contacts (dry lint free cloth), and re-seat the card (AGP slots are tricky and cards can wiggle out a little). Do this with the RAM, too. Remove the processor and then re-seat. If the PC boots up w/ no drives attached (well, it won't boot but it will run) - connect the primary HDD and then test again. Continue to do this until it doesn't power on anymore.